The specific goal of this research is to purify and characterize the structure of a heparin hexasaccharide capable of inhibiting angiogenesis. The proposed studies offer the potential of providing the first structurally defined inhibitor of angiogenesis. A team at MIT will use heparinase produced by Flavobacterium heparinum to help prepare a mixture of oligosaccharides from heparin. The MIT team will separate the oligosaccharides into di-, tetra-, hexa- and octasaccharides by gel-filtration chromatography and will deliver samples of these different-sized mixtures to a team at the University of Colorado. The MIT team will also purify other heparin-degrading enzymes to assist the Colorado team in the characterization of heparin oligosaccharides. A team at the Harvard Medical School will determine the angiogenesis-inhibitor activity of the oligosaccharides and all sub-fractions produced during purification by the Colorado team. Once homogeneous heparin oligosaccharides with and without angiogenesis-inhibitor activity have been isolated, the Colorado team will structurally characterize them and ascertain the structural features required for angiogenesis-inhibitor activity. Experimentation with the pure angiogenesis inhibitor can determine how it functions and reveal more about the nature of angiogenesis. The structure of the inhibitor must be known before the inhibitor and potential active analogs can be chemically synthesized de novo or by modification of abundant, inactive heparin fragments. Study of the inhibitor could lead to the development of drugs that might provide a new approach to anti-tumor therapy. Because angiogenesis inhibitors affect the endothelial cell population of a tumor rather than the tumor cell population directly, it is possible that such an agent may affect a wider variety of tumors and may have lower toxicity than conventional agents. The proposed study is the first step towards the development of such an agent(s). This proposal is a collaborative one by teams at the Massachusetts Institute of Technology, the Harvard Medical School and the University of Colorado, Boulder. The Principal Investigator will be the project coordinator. The project description is divided into three parts, with that of the Colorado team first, followed in order by those of the MIT and Harvard teams. A combined budget, to be supervised by the University of Colorado, and budgets for each of the three teams are provided.